[OpenSIPS-Devel] [OpenSIPS-Users] python module - bug and questions
Mundkowsky, Robert
rmundkowsky at ets.org
Fri Apr 28 09:42:55 EDT 2017
I don’t have time to setup your test jig right now. But attached are the snippets of code that fail.
You will need to the following to use them:
I am using Python 2.7.13 (via conda 4.2.13).
You will need a MySQL database.
sudo apt-get install -y libmysqlclient-dev
sudo apt-get install -y mysql-client-core-5.7 python-mysqldb
conda install MySQL-python OR sudo apt-get -y install python-pip; pip install --upgrade pip
You need to make sure opensips uses correct python (it is in PATH) and make sure python modules are reachable (in PYTHONPATH), hence if you use /etc/init.d/opensips then add those environment variables there.
Opensips modules:
db_mysql module
python module
opensips.cfg
loadmodule "python.so"
modparam("python", "script_name", "call.py")
modparam("python", "mod_init_function", "mod_init")
modparam("python", "child_init_method", "sip_child_init")
#put this anywhere it will get called
python_exec('incrementMissedCallsCountBackGround');
#or
python_exec('incrementMissedCallsCount');
Then just call opensips twice in a row or concurrently. Seemed to fail more than half of the time.
Robert Mundkowsky
From: Mundkowsky, Robert
Sent: Tuesday, April 25, 2017 4:57 PM
To: 'Maxim Sobolev' <sobomax at sippysoft.com>
Cc: OpenSIPS devel mailling list <devel at lists.opensips.org>; Bogdan-Andrei Iancu <bogdan at opensips.org>
Subject: RE: [OpenSIPS-Users] python module - bug and questions
I am guessing this is not the case. My guess is mod_init is called once by main/master openSIPS process and child_init is called for each child openSIPS process.
Hence you should modify your C code not to initialize the Python stuff in mod_init, but instead in child_init. And your Python code would also follow that change:
def child_init(rank):
inst = OpenSIPSHandler()
return inst
If you do this, then you get a separate Python thread and interpreter per child. Right now, you are getting a Python thread and interpreter that was started in a different process (the parent openSIPS process) and some of this is copied to the children and it kind of works, but some things like thread locks and real threads started by the Python thread are not copied to the child processes.
Robert Mundkowsky
From: Maxim Sobolev [mailto:sobomax at sippysoft.com]
Sent: Tuesday, April 25, 2017 3:58 PM
To: Mundkowsky, Robert <rmundkowsky at ets.org<mailto:rmundkowsky at ets.org>>
Cc: OpenSIPS devel mailling list <devel at lists.opensips.org<mailto:devel at lists.opensips.org>>; Bogdan-Andrei Iancu <bogdan at opensips.org<mailto:bogdan at opensips.org>>
Subject: Re: [OpenSIPS-Users] python module - bug and questions
Robert, what you have described is how essentially python module works. We init the interpreter and then the opensips forks, and in each of its children the mod_init() python function exported by your code is called, which returns instance whose method can be invoked via script. So at the end of the day you end up with as many independent processes as there are opensips children.
Here for example what we have in our handler:
from OpenSIPS import LM_ERR
from ser import SerHandler
class OpenSIPSHandler(SerHandler):
def www_authenticate(self, msg):
...
return rval
def mod_init():
inst = OpenSIPSHandler()
return inst
-Max
On Tue, Apr 25, 2017 at 10:25 AM, Mundkowsky, Robert <rmundkowsky at ets.org<mailto:rmundkowsky at ets.org>> wrote:
Thanks for responding. Thought you would just advise me to use specific compiler flags first.
Do you want me to use your jig (testing setup) to make a crash?
Or do you want me to add python code to your git repo so you can run it using your jig?
What you are doing with code is pretty complex for me and makes my brain want to explode.
My understanding is:
1) Python threads are not real threads, instead only one python thread runs at a time (per the global interpreter lock)
2) You are creating a Python thread (that uses one Python interpreter) in the main openSIPS process that likely loads the openSIPS user’s Python module to be used
3) Then, I assume, openSIPS main process forks children processes
a. I assume Python thread and interpreter is treated as data and code that is copied to all children processes. Note if it were a real Linux thread then it would not be copied to children processes.
b. You then use the copied Python thread in all children processes as if it is a single Python thread across the main and child processes or as if it were a single Python thread per each main or child process
I guess this might work, because if the Python thread is truly copied then you really have a different Python thread and interpreter per main and child processes. But Python documentation (https://docs.python.org/2/c-api/init.html#c.PyThreadState) states “When extending or embedding Python, there is no way to inform Python of additional (non-Python) locks that need to be acquired before or reset after a fork”, which makes me think what you are doing will not work. This is because any Python modules someone might use (e.g. MySQLdb) might use a lock in the main process that can’t get cleared in the child process.
Might be wiser to just start one Python thread and interpreter in each child process I assume is kicked off via child_init. Then you would still have the module loaded once per child. Although I am not sure if main process needs a Python thread, but probably not.
Robert Mundkowsky
From: Maxim Sobolev [mailto:sobomax at sippysoft.com<mailto:sobomax at sippysoft.com>]
Sent: Monday, April 24, 2017 10:09 PM
To: Mundkowsky, Robert <rmundkowsky at ets.org<mailto:rmundkowsky at ets.org>>
Cc: OpenSIPS devel mailling list <devel at lists.opensips.org<mailto:devel at lists.opensips.org>>; Bogdan-Andrei Iancu <bogdan at opensips.org<mailto:bogdan at opensips.org>>
Subject: RE: [OpenSIPS-Users] python module - bug and questions
Robert sorry for the delay. What could be useful if you can produce chunk of python routing code (could be NOP on the functional side) that crashes repeatedly on our voiptest jig (https://github.com/sippy/voiptests). The travis is setup to build pull requests, so that you can inject your code and let it rip. It uses similar configiration of linux / python.
-Max
On Apr 21, 2017 9:32 AM, "Mundkowsky, Robert" <rmundkowsky at ets.org<mailto:rmundkowsky at ets.org>> wrote:
Python 2.7.13 on Ubuntu 16.04.2 LTS.
How do you link using pthreads?
Do you add flags to Makefile, or will setting “USE_PTHREAD_MUTEX” and “USE_POSIX_SEM” via menuconfig do it?
Since openSIPS is not multithread, seems like it would be a lot cleaner to not use threads at all on C/C++. Then threads could still be used on Python side if needed.
Robert Mundkowsky
From: Maxim Sobolev [mailto:sobomax at sippysoft.com<mailto:sobomax at sippysoft.com>]
Sent: Friday, April 21, 2017 11:57 AM
To: Bogdan-Andrei Iancu <bogdan at opensips.org<mailto:bogdan at opensips.org>>
Cc: OpenSIPS users mailling list <users at lists.opensips.org<mailto:users at lists.opensips.org>>; Mundkowsky, Robert <rmundkowsky at ets.org<mailto:rmundkowsky at ets.org>>
Subject: Re: [OpenSIPS-Users] python module - bug and questions
Robert, what Bogdan says is essentially correct. The OpenSIPS itself is not using any threads AFAIK, therefore python module code is kept as simple as possible. Now back to the original question: we use quite a lot of python code in our routing and some of the python modules that are running are actually creating threads on their own and it appears to be pretty stable. What OS / python version are you using? What could be different in our case is that we link our OpenSIPS binary with pthreads always (which may or may not be the case on your build), so there might be some vital threads runtime infrastructure that is not getting initialized in your case.
-Max
On Fri, Apr 21, 2017 at 1:25 AM, Bogdan-Andrei Iancu <bogdan at opensips.org<mailto:bogdan at opensips.org>> wrote:
Hi Robert,
The only question I can answer is 1) - OpenSIPS it is a multi-process application (and not using threads).
How the python module is design (from threading perspective), I do not know - maybe Maxim, the author of this module can help with this.
Regards,
Bogdan-Andrei Iancu
OpenSIPS Founder and Developer
http://www.opensips-solutions.com
OpenSIPS Summit May 2017 Amsterdam
http://www.opensips.org/events/Summit-2017Amsterdam.html
On 04/19/2017 08:43 PM, Mundkowsky, Robert wrote:
Hi,
This email should likely go to your other dev forum, but I don’t have access yet.
I am using openSIPS 2.2.3 on Ubuntu 16.04.2 LTS.
I am using the python module. The python script called works fine when called from outside openSIPS and it works fine when called inside openSIPS, if it is triggered once at a time.
But if the python script is triggered twice by two phone calls or more or even one call after another in short order, then there are weird errors which show up in different places in the code like:
ERROR:python:python_handle_exception: #011TypeError: an integer is required
I am guessing the openSIP python module has some problem/s related to threading.
Questions:
1) I am guessing that OpenSIPS uses a multi-threaded architecture?
2) Is the python module meant to be a single thread? Or multi-threaded?
a. If it is meant to be single threaded then why use python library thread functions? Just use python library without multi-threaded stuff.
b. If it is meant to be multi-threaded then why is there only one call to PyThreadState_New and myThreadState is a global used everywhere?
i. I would think a thread per call to python_exec would make more sense and make the code easier to understand?
3) Also why is there no clean up code (PyThreadState_Clear, PyThreadState_Delete, Py_Finalize)?
a. I am guessing the idea is you do not need clean up, because it only happens when openSIPS is turned off.
Robert
For reference:
https://www.codeproject.com/articles/11805/embedding-python-in-c-c-part-i
http://www.awasu.com/weblog/embedding-python/threads/
http://stackoverflow.com/questions/26061298/python-multi-thread-multi-interpreter-c-api
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Maksym Sobolyev
Sippy Software, Inc.
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This e-mail and any files transmitted with it may contain privileged or confidential information. It is solely for use by the individual for whom it is intended, even if addressed incorrectly. If you received this e-mail in error, please notify the sender; do not disclose, copy, distribute, or take any action in reliance on the contents of this information; and delete it from your system. Any other use of this e-mail is prohibited.
Thank you for your compliance.
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Maksym Sobolyev
Sippy Software, Inc.
Internet Telephony (VoIP) Experts
Tel (Canada): +1-778-783-0474
Tel (Toll-Free): +1-855-747-7779
Fax: +1-866-857-6942
Web: http://www.sippysoft.com
MSN: sales at sippysoft.com<mailto:sales at sippysoft.com>
Skype: SippySoft
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This e-mail and any files transmitted with it may contain privileged or confidential information. It is solely for use by the individual for whom it is intended, even if addressed incorrectly. If you received this e-mail in error, please notify the sender; do not disclose, copy, distribute, or take any action in reliance on the contents of this information; and delete it from your system. Any other use of this e-mail is prohibited.
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